Molecular cloning of p125(Nap1), a protein that associates with an SH3 domain of Nck

Binding proteins to the Src homology 3 (SH3) domains of Nck were screened by the use of glutathione S-transferase fusion proteins. Two proteins of 140 and 125 kDa were detected, both of which associated preferentially with the first SH3 domain of Nck. The 125-kDa protein, designated as Nap1 for Nck-associated protein 1, was purified and the corresponding rat cDNA was isolated. The predicted amino acid sequence revealed that p125(Nap1) dose not contain any known functional motif but shows sequence homology to Hem family gene. Using specific antibodies, p125(Nap1) was shown to associate with Nck both in vitro and in intact cells. Further characterization of p125(Nap1) may clarify the protein-protein interaction in the downstream signaling of Nck. (C) 1996 Academic Press, Inc.